Centrifuges



SePt- 20, 1950 E. v. JUNG E'rm. 2,953,250

CENTRIFUGES Filed Nov. 14, 1956 ZISheetS-Sheet 1 Fg.l

Sept. 20, 1960 E, v, JUNG ETAL v 2,953,250

CENTRIFUGES Filed NOV. 14, 1956 I 2 Sheets-Sheet 2 s-drum as far a'spossible.

' screen.

United States Patent 2,953,250 CENTRIFUGES Erland Viktor Jung, SvenHilding Montus, and Nils 'Vilhelm Andersson, Lands'krona, Sweden,assignors to `Aktiebolaget fLandsverk, fL'andskrona, vSweden nFiled Nov.14, 1956, Ser. No. 622,128 Claims priority, application ySweden July '6,1956 Z Claims. (Cl. 210-375) :ment along the 'inside of 'thefdrum by `adisplacement -of the shaft in its '-longitudinal direction. The presentinvention has for its object by a suitable construction of the scraperand itsmotion kmechanism to vimprove the modeof operation of fthescraper and to facilitatecomplete removal yof the remaining material ina manner to spare the strainer 'screen-on ythe inside of the centrifugeThe invention is principally rdistinguished by the lfeature .that -thescraper is ,pivotally connected to an arm extending -ffrom the rockingshaft thereof, at a point of the arm which is located, relatively to therocking shaft, on 'the opposite side of the radial plane extendingthrough the axis .of rotation of =the centrifuge and the point ofcontact of the :scraper V'ontheinside of the drum.

The invention will be described Vmore'closely with reference `to :theaccompanying drawings, which illustrate j a-'sugar centrifuge providedwith a `scraper contrivance according to the invention. Fig. l is avertical view of the contrivance together with adjacent parts of thecentrifuge. Fig. 2 is a cross section Ialong a horizontal plane a-a inFig. l. Fig. 3 is a vertical view of the scraper proper, and Fig. 4 is ahorizontal view of the same.

The centrifuge drum 1 is mounted with its shaft 2 and the driving motor3 in a frame consisting substantially of a girder system 5 arranged onlegs 4. The cylindrical jacket of the drum is perforated and providedwith a strainer screen 6 on the inside thereof. It is covered by a cap7, which is provided with an opening for the scraper. The drum issurrounded by a cylindrical mantle 8, which is likewise provided with acap 9. The caps 7 and 9 are omitted in the plan View shown in Fig. 2.

During the centrifugation the sugar juice escapes through the strainerscreen and the jacket of the drum to a non-illustrated collectingreceptacle arranged beside the mantle 8, whereas the remaining solidsugar mass forms a cylindrical body 10 on the inside of the strainer Theremoval of this material is effected by means of a blade-like scraper11, which is secured to the lower end of a shaft 13 parallelling thecentrifuge shaft. The shaft 13 is `rotatably and displaceably mounted ina concentric guide sleeve 14, which is secured to the girder system 5 aswell as to a bracket 15 extending from the leg 4. The upper end 16 ofthe shaft 13 is threaded and guided in a sleeve 17. The shaft 13 isadapted to be raised and lowered by means of a motion transmittingcontrivance built into a hous- Acal Vportion of the arm 'strainer 16maybe accurately a vertical edge 30, which is operative duringthe-:outward swinging movement 'of the scraper toward ithe finside ofthe centrifuge drum,

ing 18 and 'comprising a rotating nutscrewed onto the threaded portion16 `as `well 'vas Va worm ygearing .connected to said nut, the drivingshaft of which gearing lis adapted to :be driven from an electriclrnotor V19 through a belt transmission arranged'withima casing 20.Theemotor1=91is adapted to operate automatically-under the control .of'limit switches 21 r'and 22, which are actuated 'by pin 23 movable withthe worm shaft 16. Arranged on the'non-threadedportion'of vtheshaft 13isguide pin l24 provided with a roller engaging ya guide slot 25vin zthesleeve '14, said guide lslot vcomprising -a `spiral-shaped portion 2.6and a straight portion connected thereto.

As will appear from Figs. 3 and 4, the scraper 11 consists of asheet-metal member having an outwardly flange intended to force the 11is ypivotally connected to the vertical outer end of the arm 12 `bymeans of a leaf spring .27, which is welded on the one -side thereof to'.the lscraper while being secured on the other side thereof to the armby means of screws 28. The springnormally tends to keep the scraper inthe position lshown by full lines in Fig. '4. When the scraper isbrought into engagement with the material cylinder 10, the workingpressure of the scraper will shift the latter -into the position shownby broken vlines inFig. 4, wherein the `scraper bears on 'two screws 29arranged on the verti- :12, by means of which screws the operativeposition of the .scraper relatively .to .the adjusted. The *scraper hasy'the drum. The scraper and is also provided Ywith ia lower horizontal`edge 31,which is operative duringv the :axial displacing 'movement ofthe scraper. v

'During centrifugation the scraper -assumes `the position shown by fullVlines :in vrFig. .2. The vcentrifugation ,having been terminated, the.centrifuge .drum iisy braked .to a number of revolutions :suitable for'theemptying .of :the centrifuge. Atthis number ofrrevolutions the:motor 19 is yautomatically brought into operation, to commence with ata relatively low number of revolutions, the shaft 13 being screweddownwardly thereat and the scraper performing rst a swinging movement,while the guide pin 24 moves in the guide slot 26 from the position Ainto the position B, wherein the guide pin is at the upper end of thestraight portion of the guide slot. The scraper will then have movedfrom the position A1 into the position B1 shown by broken lines. Duringthis movement the scraper will have cut out an annular groove in theupper e-nd of the material cylinder 10 and will have removed acorresponding quantity of the material. Under the iniluence of thepressure of the material on the scraper the latter is shifted into theposition shown by broken lines in Fig. 4. At the termination of theswinging movement the scraper is caused to be-ar lightly with itsvertical edge against the strainer screen 6. By means of the set screws29 the position of the scraper relatively to the strainer screen may beaccurately adjusted, so that the strainer screen will not be subjectedto any appreciable wear. If desired, the position of the edge 30 may beadjusted so that a slight play is provided between the edge andtherstrainer screen.

When the guide pin 24 reaches the position B, the circuit of the motor19 is switched by means of the contact 21, so that the motor will rotateat a considerably higher number of revolutions. During the continuedmovement the shaft 13 is nguided by means of the pin 24 in the straightportion of the slot 25, the shaft being thus displaced downwardly in itslongitudinal direction without being turned. Hereby the remainingportion o-f the material cylinder is scraped olf during the movement ofthe scraper from the position B1 into the bottom position C1, the guidepin 24 having thus reached the position C. In the position the contact22 is actuated, and the motor circuit is interrupted while a time relayis switched in at the same time. During a period of time controlled bythis time relay the scraper remains in the bottom position, until all ofthe material has been removed. At the end of this period the motorcircuit is switched, and the scraper is raised into its initial positionat a guidance of the shaft 13 in the slot 25. After that, the number ofrevolutions of the centrifuge drum is increased, and a further quantityof material is supplied, which is then subjected to centrifugation.

After the scraper has been relieved of the pressure of the material inthe bottom position of the scraper, the latter will spring back into theposition shown by full lines in Fig. 4. During the vertical returnmovement the edge 30 of the scraper will thus take a position in whichit is raised from the strainer screen, whereby the latter is spared. Theswinging movement of the scraper in a direction inwardly from thestrainer screen under the influence of the leaf spring 27 is `renderedpossible by the fact that the scraper 11 is pivotally connected to thearm 12 at a point of the arm near the spring 27, which in the workingposition of scraper 11 is located behind the radial plane extendingthrough the axis of rotation 2 of the centrifuge and the contact pointof the scraper on the inside of the drum, counted in the rotationaldirection of the drum. Under certain circumstances, depending forinstance on the consistency of the material, the scraper might besubjected to so powerful a pressure that the torsional moment exerted onthe scraper shaft 13 becomes greater than the moment created by thetorsional forces in the shaft 13. The scraper will thereby be swungabout the axis of the shaft 13 over an angle, which is obviouslycomparatively small, the scraper will be lremoved from the strainerscreen, but which is sufficient to move the outer end of the scraper outof contact with the strainer screen, whereby damage of the strainerscreen is prevented. This is made possible by the fact ythat the rockingshaft 13 of the'scraper is located in front of the radial planeextending through the axis of rotation of the centrifuge and the contactpoint of the scraper on 4 the inside of the drum, counted in therotational direction of the drum.

The rocking shaft 13 of the scraper and the swinging axis determined bythe leaf spring will thus be located on opposite sides of said radialplane. The rocking shaft 13 is preferably located inside the jacket ofthe centrifuge drum but may possibly be disposed outside the same,provided that the scraper carrying arm 12 is extended suiciently in thevertical direction.

What is claimed is:

1. In a centrifugal separator, the combination comprising a centrifugedrum mounted on a vertical driving shaft, a fixed guide member, aVertical scraper shaft movable in s'aid guide member, `alaterally-projecting arm secured to the lower end of the scraper shaft,a blade-like scraper disposed to remove solid material from said drum,said scraper being swingably connected at one end to the outer end ofsaid arm and being `acted upon by a spring to allow the free end of thescraper to be swung outwards against the action of the spring, a stopmember on said arm for limiting the outward swinging motion of thescraper relatively to said arm, a driving mechanism for displacing thescraper shaft longitudinally, and means for rocking the scraper shaftand swinging the scraper to land from the inside of the centrifuge drum`and for guiding the scraper along the inside of the drum', said scrapershaft and said spring being disposed on opposite sides of the radialplane extending through the yaxis of rotation of the centrifuge and thefree end of the scraper when brought in contact with the inside of thedrum.

2. A centrifugal separator as defined in claim 1, wherein said meanscomprises a cam slot formed in said fixed guide member and a projectingguide pin provided on said scraper shaft and extending through said camslot, a threaded portion on said scraper shaft and a driving nutreceiving said threaded portion for displacing the scraper shaftlongitudinally.

References Cited in the le of this patent UNITED STATES PATENTS1,102,530 Mackintosh July 7, 1914 1,431,016 Mackintosh Oct. 3, 19222,467,023 Foster Apr. 12, 1949 2,667,974 Hert-rich Feb. 2, 19542,755,991 Tholl July 24, 1956

